NodeJS In Practice

by Quy Tran

@tuanquynet on Google+, Twitter, Github

About Me

• I was Frontend Team Manager at Pyramid Consulting
• I am a technical lead at NAU Studio
• I was Flash Developer, Frontend Developer
• I am Fullstack Developer

Contents

• Take advantage of latest feature of language (ES6)
• Setup correct development environment
• Establish coding style in development team
• Secure Application Server
• Debug NodeJS application
• Profiling NodeJS application
• Monitor NodeJS application

Latest feature of javascript

• let, const
• object literal
• template literal
• arrow function
• destructuring
• iterator
• generator
• promise

Sample Code

const crypto = require('crypto');
const fs = require('fs');

class Utils {
	
	decodeBase64(base64str, file) {
		const p = new Promise((resolve, reject) => {
			// create buffer object from base64 encoded string, it is important to tell the constructor that the string is base64 encoded
			var binary = new Buffer(base64str, 'base64');
			// write buffer to file
			fs.writeFile(file, binary, (err, result) => {
				if (err) {
					reject(err);
				} else {
					resolve(result);
				}
			});
		});
		return p;
	}

}

module.exports = new Utils();

Sample Code

UserModel.observe('before save', function (context, next) {
	let data = context.instance ? context.instance : context.data;
	
	const hasBase64InAvatar = (data.avatar || '').indexOf('base64,') > -1;
	let [fileType, base64] = [];
	if (hasBase64InAvatar) {
		[fileType, base64] = data.avatar.split('base64,');
		data.base64 = base64;
		[, fileType] = fileType.split('/');
	}

	let fileName = data.username || (context.currentInstance ? context.currentInstance.username : new Date());
	if (fileType) {
		fileType = fileType.replace(';', '');
		fileName += fileType ? '.' + fileType : '';
	}

	// We need to add roles to user if uploading data has roles
	let allPromises = [];
	if (_.isObjectLike(data.roles)) {
		const roles = _.isArray(data.roles) ? data.roles : [data.roles];
		allPromises.push(UserModel._addRoles({roles, userId}));
		delete data.roles;
	}

	if ((data.base64 || '').length > 100) {
		allPromises.push(
			new Promise((resolve, reject) => {
				UserModel
					._saveImage(data.base64, fileName)
					.then((result) => {
						data.avatar = result;
						resolve(true);
					})
					.catch((err) => {
						reject(err);
					});
			})
		);

		delete data.base64;
	}
	Promise.all([...allPromises]).then((values) => {
		console.log('resolve all ', values);
		next();
	});
});

Setup Development Environment

• Use latest LST version of NodeJS
• Manage NodeJS dependencies
• Using npm to create build script
• Code linter
• Unit Test

Establish Coding Style

• Coding convention
• All dependencies should be required at top of file
• Import only what we need
• Standardize the way of controlling async flow